Mean flow distortion due to finite‐amplitude instability waves in a plane turbulent wake

The nonlinear interaction between the mean flow and a coherent disturbance in a two‐dimensional (2‐D) turbulent wake is investigated. Based on considerations from stability theory, a model that assumes a quasiparallel mean flow and constant eddy viscosity is developed. Detailed comparisons between the model and experimental results are made. It is found that for downstream distances, where the wave is still being amplified according to the linear stability theory, the model predicts very well the modification of the mean velocity profile and the spatial growth of both the forced wake and the disturbance amplitude.